QCA based sequential and combinational circuit design and importance of parasitic components

As the scaling of transistors has reached its nadir [6], [7], the valid replacement for the CMOS technology to achieve further advancements in the circuits, on the parameters of low power and area occupancy has become an immediate necessity. QCA is one of the greatest potential device technologies ever proposed till date, for the replacement of CMOS Technology. This paper presents the basic theory of Quantum dots with the technology involved in its fabrication, followed by the introduction of QCA including its fundamental concepts i.e. polarization and clocking and, its basic gate (inverter, majority gate) implementations. The working mechanism of complex circuit is given deep glance and, the problems faced during their implementation and working are identified. JK Flip-Flop is used as an example of complex circuitry to understand mechanism and identify problems. At last, the solutions for the identified problems are provided. The output waveforms are provided to demonstrate the behavior of faulty as well as the modified fault free circuits. These designs are captured and simulated using a designing tool called QCA Designer.